Method and apparatus for controlling electro-pneumatic braking on a train

ABSTRACT

Method and apparatus for controlling braking on a train having ECP railcars using a conventional automatic brake valve. The locomotive and railcars are connected to brake pipe and a wireline, or use RF communications. A brake handle or other brake control valve interface is operated to cause a pressure change in an equalizing reservoir. The relay valve is isolated from the pressure change and connected to a reference pressure whereby brake pipe pressure is maintained. The pressure change is sensed and a signal generated representative thereof which is used to determine the level of braking commanded on the railcars. The apparatus includes an interface unit interposed between pertinent ports connecting the automatic brake valve, equalizing reservoir and brake pipe, and an equalizing reservoir pressure sensor to provide an output signal to an ECP controller for controlling braking on the railcars.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 09/840,589, filed Apr. 23, 2001 now U.S. Pat. No.6,626,506.

BACKGROUND

The present invention relates generally controlling electro-pneumaticbraking on railway train of railcars having electrically controlledpneumatic (ECP) brake equipment, and more particularly to a method andapparatus for controlling the braking on such ECP equipped railcars froman automatic brake control valve on a locomotive of the train, whichautomatic brake valve conventionally controls the train brakespneumatically via a brake pipe interconnecting the locomotive and therailcars. An example of such an automatic brake valve is a Type 26automatic brake valve manufactured by Westinghouse Air BrakeTechnologies Company (“WABTEC”™), or other types of locomotive brakecontrol valves which operate in the same general manner. Controlling theapplication of brakes on ECP equipped railcars using a conventionalautomatic brake valve provides a manner of control which is similar inappearance and operation to existing pneumatic braking equipment fromthe train operator's standpoint, while incorporating the advantages ofECP braking, as discussed in detail hereinafter.

The existing standard method of controlling air brakes on trains usingan automatic brake valve involves pressurizing a fluid passageway, andits associated connectors and fittings, known collectively as the brakepipe, to which the locomotive and each railcar is interconnected. Inparticular, such automatic brake valves can operate the train brakes bythe train operator initiating pressure changes in an equalizingreservoir via the automatic brake handle, or other automatic brake valveoperator interface. The pressure change in the equalizing reservoir, ora similar pressurized control volume, can be mirrored in the brake pipeby a relay valve, which is typically a portion of the automatic brakevalve. The pressure change in the brake pipe is then detected by brakeequipment on each railcar, which is connected to the brake pipe, andused to control the level of braking on the railcar. Conventionally,each railcar has equipment for applying the brakes, including an airreservoir which is typically divided into two portions—an emergencyportion and an auxiliary portion, and a pneumatic brake control valvefor applying and releasing the brakes on the railcar. One such railcarbrake valve is, for example, an ABDW™ valve manufactured by WABTEC™.However, it should also be understood that there are other types ofrailcar brake control valves besides the ABDW™ which operate in the samegeneral manner. The such railcar brake control valves can typically havea service portion—for service level brake applications, and an emergencyportion—for emergency brake applications. The auxiliary and emergencyreservoirs are normally charged from the brake pipe to a predeterminedpressure, which is set by the train operator, using what is commonlyreferred to as the “feed valve.” Once the brake pipe on a train has beencharged to the feed valve setting, the brake equipment of thecontrolling locomotive, when so equipped, will maintain the desiredpressure against slight to moderate leakage.

In order to apply the brakes on the train, the operator typically usesan interface, or control portion of the automatic brake valve, which istypically the brake handle, but could be any other type of operatorcontrol portion or device, to reduce the pressure in the brake pipe by aselected amount. A low to moderate reduction of pressure in the brakepipe will cause the service portion or the railcar brake control valveto admit air from the auxiliary reservoir into the brake cylinder, inproportion to the amount of reduction in brake pipe pressure, to applythe brakes on the railcar. Subsequent reductions in brake pipe pressurewill cause greater brake cylinder pressure, up to the point at which thepressure in the auxiliary reservoir is permitted to equalize with thepressure in the brake cylinder. If a greater amount of brake cylinderpressure is desired, the brake pipe pressure can be rapidly reduced tozero, which will cause the railcar brake control valve emergency portionto add the volume of the emergency reservoir to the combined auxiliaryreservoir and brake cylinder pressure.

Due to the design of freight car brake equipment, as well as theproperties of compressed air in the brake system, an incremental, or“graduated” release of the brakes on a freight train is not possible.The operator can release the brakes on the each railcar only by movingthe handle of the automatic brake valve to the “release” position,thereby restoring the pressure in the brake pipe to the previouslyestablished feed valve setting. In response to the rise in brake pipepressure, the brake control valves on the each railcar will vent thebrake cylinder to release the pressure, and also couple the auxiliaryand emergency reservoirs to the brake pipe to restore the pressure ineach reservoir to the desired setpoint.

It should be understood that the movement of pressurized air within thebrake pipe is typically restrained by various factors, such as bends,branch pipes, rubber hoses, couplings, and the like. Therefore, uponinitiation of a brake application by the train operator, via a reductionin brake pipe pressure, a lengthy delay may occur until the brakes atthe rearmost railcars of the train begin to develop significant brakingeffort. As a result, an unequal application of the brakes occurs throughthe train, due to the amount of time it takes for the pressure reductionin the brake pipe to propagate through the brake pipe from thelocomotive to the rearmost railcars in the train. A consequence ofnon-uniform braking on the railcars from front of the train to rear isthat serious tensile or compressive forces can be generated in thetrain, which can cause serious train handling problems.

Similarly, when releasing the brakes following an application, air mustflow into the brake pipe from the front of the train, and release of thebrakes on each railcar occurs, like the brake application processdescribed above, in a sequential manner, rather than simultaneously aswould be preferred. Again, serious consequences may result from the thusgenerated in-train forces, especially at slow speeds.

In order to eliminate several of the perceived shortcomings of theconventional pneumatically implemented train braking control system, anECP brake system has been developed by which each railcar can developtruly simultaneous brake applications and releases through the use of acable, commonly called a trainline, connected between the various carsof the train. Alternatively to the use of a trainline, radiocommunication control could be utilized between the locomotives and therailcars. The trainline can provide two functions: 1) a source ofcurrent from which the electronic equipment on each car can charge localbatteries, and 2) a pathway by which electrical control signals can becommunicated to cars and other locomotives so equipped.

In the ECP braking system, trains made up of cars and locomotives soequipped can operate in such a fashion that the brake pipe no longerserves as both a supply and control line, but becomes only a means bywhich air is supplied to the cars for charging their reservoirs andsupplying brake cylinder pressure. Applications of the brakes on thecars can instead be accomplished by means of an electrical signal on thetrainline, or by radio communication. Each railcar, and additionallocomotives when used, in the train can receive command signals andapply or release the brakes on the car according to the level of brakingcommunicated in the command signal.

Since all of the brakes on the train will apply in parallel, rather thanserially, smoother handling of the train can be achieved with lesschance of damage to the train or its cargo. A second benefit of the ECPsystem is that the brake cylinder pressure on the various railcars cannow be released in incremental steps. This graduated release allows thetrain operator to gradually reduce the braking effort on the trainwithout danger of having the train pick up excessive speed from havingto fully release the brakes on all of the railcars.

Presently known ECP system are fully electronic, using components suchas magnet valves and transducers to develop the required level of airpressure in the brake cylinders. The existing brake equipment inconventional locomotives, i.e., non-electronic brake control valves,operates by controlling air pressure mechanically. Therefore, forconventional brake control equipment in locomotives to be able tocontrol the brakes on ECP equipped railcars, an additional piece ofequipment, called a Head End Unit (HEU), it typically added to permitthe train operator to control braking on the railcars. However, the HEUcompetes with space in the already crowded locomotive cab. To controlECP braking on the railcars, such HEUs typically includes a variety ofpush-button controls, requiring the train operator to use thisadditional train brake control device to operate the brakes on therailcars in ECP mode. This is also in contrast to the movement of thebrake handle typically used on conventional non-electronic locomotiveautomatic brake control valves to which the operator is accustomed.

Accordingly it would be desirable to provide a brake control systemwhich permits a train operator to control the brakes on the railcars inan ECP manner using the existing pneumatic locomotive brake controlvalve. Moreover, the brake handle commonly used with such brake valves,with which the train operator may be comfortable, can also be used tocontrol the ECP braking on the railcars, thus integrating the operationof the ECP braking system with the conventional pneumatic locomotivebrake control valve such that an additional ECP brake control device isnot required.

SUMMARY

In its most basic form, the invention provides a method and apparatusfor controlling the braking on ECP equipped railcars using aconventional automatic brake valve by converting the pressure changescreated by the automatic brake valve, which constitute the pneumaticbrake command signals that are normally used to control train brakingvia the brake pipe, to signals which can be communicated via a brakecontrol signaling system, such as a trainline or RF communicationsystem, by which the locomotive and railcars are inter-connected. Theconverted signals are thus used to control ECP braking on the railcarsvia the brake control signaling system. In particular, the apparatus caninclude an interface unit for interrupting pertinent pneumaticconnections between the automatic brake valve and the equalizingreservoir, such that a pressure change initiated via the automatic brakevalve is not mirrored in the brake pipe, as typically occurs in responseto a pressure change in the equalizing reservoir, to control braking onthe railcars. Instead, the apparatus can include a pressure sensor fordetecting such pressure change and converting the pneumatic signal to anoutput electrical signal. This output signal is then communicated to anECP control device which uses the signal to control braking on therailcars in an ECP manner via the brake control signaling system. Theinterface unit can also connect the automatic brake valve to aregulating valve, the output of which is maintained at the feed valvesetting, thus generally maintaining the brake pipe pressure at the feedvalve setting such that the brake pipe is continuously charged.Moreover, the interface unit can used to both isolate the brake pipefrom the automatic brake valve and connect the equalizing reservoir withthe aforementioned pressure sensor. The ECP control device whichcontrols braking on the railcars can simply be a device which receivesthe pressure sensor output signal and determines therefrom the desiredlevel of braking to be commanded on the ECP equipped railcars. The ECPcontroller can operate autonomously, requiring no attention from thetrain operator. Consequently, the conventional automatic brake valve canbe used to control the braking on ECP equipped railcars without the needfor a separate, additional ECP brake control device in the cab of thelocomotive to control ECP braking.

Similarly, a method of controlling braking on ECP equipped railcars caninclude the steps of: using a conventional automatic brake valve tocreate a pneumatic brake command signal; converting the pneumatic brakecommand signal to a signal which can be communicated via a brake controlsignaling system; and controlling braking on the railcars based upon theconverted signal. Additional steps can include isolating the brake pipefrom the pressure change and maintaining the brake pipe at apredetermined pressure. In more detail, the method can include isolatinga pressure change in the equalizing reservoir from a relay valve portionof the automatic brake valve, such that the relay valve portion does notcause the brake pipe pressure to mirror the equalizing reservoirpressure according to the conventional functioning of the automaticbrake valve; sensing the pressure change caused in the equalizingreservoir; communicating a signal representative of the pressure changein the equalizing reservoir to an ECP controller; and controllingbraking on the ECP equipped railcars based upon such signal. Inaddition, a pressure gauge can be provided along with various pressureswitches for permitting the brake system to perform certain specificbrake functions while the interface unit is interposed in the system.

Other details, objects, and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings figures of certain embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the invention can be obtained byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates the major components of a train braking systemaccording to a presently preferred embodiment of the invention.

FIG. 2A illustrates a conventional pneumatic automatic brake valve.

FIG. 2B illustrates an alternative conventional pneumatic automaticbrake valve.

FIG. 3A diagrammatically illustrates an embodiment of the invention withthe interface deactivated such that the brake system operates in theconventional manner.

FIG. 3B diagrammatically illustrates an embodiment of the invention withthe interface activated such that the brake system operates inaccordance with the invention.

FIG. 4A is a diagrammatic illustration of an alternative embodiment ofthe invention with the interface deactivated.

FIG. 4B is a diagrammatic illustration of an alternative embodiment ofthe invention with the interface activated.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Prior to discussing the invention, it may be helpful to provide anoverview of the major elements of a train braking system according toone presently preferred embodiment of the invention, shown in FIG. 1.Additionally, the conventional manner of controlling train brakespneumatically, via a conventional pneumatic automatic brake valve like,for example a WABTEC™ Type 26™ locomotive brake valve 10, will bedescribed in connection with FIG. 2.

FIG. 1 generally illustrates the major components of a train brakingsystem according to the invention, including a locomotive 1 havingpneumatic brake equipment represented collectively as reference number2, which can be connected to a train brake pipe 3. Additionally, eachrailcar 6 can be provided with ECP brake equipment, representedcollectively as reference number 7, which can also be connected to thebrake pipe 3, and to a wireline 4. Alternatively, a radio communicationsystem 5, shown in phantom lines, could be utilized as the manner ofcommunicating control signals to the ECP equipped railcars 6 instead ofthe wireline. An ECP controller 8 can be provided on the locomotive 1 incommunication with the pneumatic brake equipment 2 for interfacing thepneumatic brake equipment 2 with the ECP brake equipment 7 on eachrailcar 6. Generally, the ECP brake equipment 7 on the railcars 6 canoperate according to existing practice, and can simply receive controlsignals from the ECP controller 8 according to the invention, asdescribed hereinafter, for controlling the brake functions on therailcars 6.

According to the invention, the brake control equipment 2 on thelocomotive 1 can include both conventional pneumatic equipment, such asan automatic brake valve, and specialized brake control equipmentaccording to the invention. The automatic brake valve can be of aconventional type, such as shown in FIG. 2A or 2B, and similar suchautomatic brake valves. The specialized brake equipment utilizedaccording to the invention can be as shown in FIGS. 3A through 4B.

Referring to FIG. 2A, a Type 26™ automatic brake valve 10, which is anautomatic self-lapping brake valve, is shown arranged with a pipebracket 16, an can include two main portions: (1) an automatic portion13, designed for regulating the pressure in the train brake pipe 3; and(2) an independent portion 19 for controlling the braking on thelocomotive independently from the train brakes. The automatic portion 13is mounted on the top of the pipe bracket 16 and the independent portion19, including the “independent brake” handle 21, is mounted on the frontof the pipe bracket 16. All pipe connections are made to the pipebracket 16. The pipe connections to the pipe bracket 16 are designednumerically, and are so identified in FIG. 2A by the reference numbershaving the prefix “P.” Note that pipe connection P1 is the port to thebrake pipe 3 shown in FIG. 1. The automatic brake valve 10 can alsoinclude a cut-off valve portion 22 for the purpose of cutting in andcutting out the automatic brake valve 10, and to permit tests for themeasurement of brake pipe 3 leakage. The cut off valve portion 22 canhave a switch 23 for selecting between up to three positions, eachcorresponding to three different modes of operation of the automaticbrake valve 10 “freight,” “passengers” and “out.” The “out” mode is usedonly when hauling the locomotive “dead” or as a trail unit in multipleunit operation. In the “freight” mode, only direct release of brakes isenabled, whereas in “passenger” mode, incremental increases inequalizing pressure are enabled to permit a graduated release of trainbrakes. However, this is permissible only in circumstances where boththe locomotive 1 and the railcars 6 are equipped to provide a graduatedrelease of the brakes, such as in certain passenger train applications.

The automatic portion 13 of the automatic brake valve 10 is itselfcomprised of several interrelated components, including a feed valveportion 25, a relay valve portion 28 and an operator control portion,typically the brake handle 31. Other components of the automatic brakevalve 10 include a brake pipe cut off valve 34, vent valve 37, emergencyvent valve 40, suppression valve 43, and equalizing reservoir cut offvalve 46. The exact function and operation of these other components isbeyond the scope of this description and would be generally beunderstood by one of ordinary skill in the art of train braking systems.This information is also not necessary for a full and completeunderstanding of the present invention.

The feed valve portion 25 is conventionally employed to set thepressure, by turning a screw 49, in an equalizing reservoir on thelocomotive, typically during initial train setup. This pressure iscommonly referred to as either the “train operating pressure” or the“feed valve setting.” The equalizing reservoir pressure is generallymaintained at this setting and it is not thereafter adjusted unless thetrain is brought to a complete stop. Adjustment of the equalizingreservoir pressure can be made when the brake handle 31 is in releaseposition by turning the adjustment screw 49 on the regulating valve 25,but only when the locomotive is not moving.

In FIG. 2B, a different, newer type of automatic brake valve 11 isillustrated. This is generally known as WABTEC™ Type 30-CDW™ automaticbrake valve equipment. This newer design brake valve equipment 11 cangenerally be substituted for the older Type 26™ brake valve 10 shown inFIG. 2A. It includes a first module 14 which has both the brake handle31′ and the independent brake handle 21′. Additionally, a second modulecan comprise a relay valve portion 28′ which operates generally asdescribed previously in regard to the relay valve portion 28 of theautomatic brake valve 10. In fact, all of the ports for the automaticbrake valve 11 can be the same as for the automatic brake valve 10, and,as such, are also numbered with the prefix “P” in the same manner as inFIG. 2A. Essentially, the automatic brake valve equipment 11 operates inthe same way as the automatic brake valve 10. Moreover, as explainedpreviously, there are also other types of similarly functioningautomatic brake valves, but such automatic brake valves generallyoperate in the same basic manner that has been described above withregard to the automatic brake valves 10 and 11.

A simplified diagram of various connections of an automatic brake valve12 to other components of the brake system 2 according to the inventionis shown in FIGS. 3A–4B. The automatic brake valve 12 can generallycorrespond to such conventional automatic brake valves 10, 11, describedabove in connection with FIGS. 2A and 2B, as well as other types ofsimilarly operating automatic brake valves. In addition to the previousdescription with respect to the automatic brake valve 10, and withreference to FIG. 2A, the feed valve portion 25 can also be affected bymovement of the brake handle 31, specifically by the cam 55 on the brakehandle shaft 58 which adjusts the air pressure in the equalizingreservoir 52 via a charging pipe into port P15. Although not implementedin exactly the same way, movement of the brake handle 31′ of theautomatic brake valve 11 can cause the same resulting pressure change inthe equalizing reservoir 52. This pressure can be externally connectedthrough a device, such as a P2A Brake Application Valve 72, to anequalizing reservoir control pipe into port P5, which leads to the outerdiaphragm chamber 61 of the relay valve portion 28. The relay valveportion 28, is a diaphragm operated valve which causes a pressure to beestablished in the brake pipe 3 that is generally equal to the pressurein the equalizing reservoir 52. Similarly, the relay valve portion 28′of the automatic brake valve 11 can also cause the pressure in the brakepipe 3 to mirror the pressure in the equalizing reservoir 52. As can beseen best in FIG. 2A, equalizing reservoir pressure acts on the outerface 63 of the diaphragm 66 and brake pipe 3 pressure acts on theopposite face 69. The relay valve portion 28 either increases or reducesbrake pipe 3 pressure in response to changes in the equalizing reservoirpressure acting on the outer face 63 of the diaphragm 66. During brakeapplications, the equalizing reservoir pressure on the outer face 63 ofthe diaphragm 66 is reduced, causing the relay valve 28 portion toexhaust brake pipe 3 air to obtain an equal reduction in brake pipe 3pressure. When the pressures on each face of the diaphragm areequalized, the self-lapping feature of the relay valve portion 28generally maintains the brake pipe 3 pressure against overcharges andpermissible train leakage. When a release of train brakes is commanded,equalizing reservoir pressure is restored to the pressure set by thefeed valve portion 25. This then causes the relay valve portion 28, topressurize the brake pipe 3 from main reservoir pressure until thepressure on both faces 63, 69 of the diaphragm 66 equalize again, atwhich point the relay valve 28 returns to its lapped position.

Typically, on valves such as the automatic brake valve 10, the brakehandle 31, or other operator control portion or interface, is used bythe train operator to control the brakes on the train by implementingpressure changes in the equalizing reservoir. These pressure changes arethen mirrored in the brake pipe 3 by the relay valve portion 28 in orderto pneumatically signal the brake equipment on articulated railcars forimplementation of braking functions on the railcars. It should beunderstood that, although described mainly in the context of thecomponents and operation of the automatic brake valve 10, the automaticbrake valve 11, and other similar automatic brake valves, generallyoperate, functionally, in the same manner even though the exactcomponents and manner of control may be different.

In any event, according to the present invention, the manner ofinitiating a pressure change, which is generally indicative of a brakecommand, need not be limited to using a “brake handle” and it should beunderstood that persons of skill in the art could devise other ways topermit the train operator to initiate such pressure changes from anautomatic brake valve without using a “brake handle.” For example,systems are known which utilize push buttons to activate valves whichcause the pressure change. Thus, the use of a brake handle itself is notrequired to achieve the benefits of the invention, which is instead moregenerally describes converting a pressure change, initiated via anautomatic brake valve, to a signal, for example an electrical signal,which can be communicated to railcars, such as by a wireline or RFcommunication system, and thus utilized to control braking on therailcars in an ECP manner. Consequently, any operator control portionwhich interfaces with an automatic brake valve may be used to initiatesuch a pressure change.

Although described in the particular context of the automatic brakevalve 10 shown in FIG. 2A (for convenience), it should be understoodthat the following description could generally be applicable to theautomatic brake valve 11 shown in FIG. 2B. The brake handle 31 istypically movable through a range of “zones” or positions. Generally athere is a “service” zone, which is a range of movement wherein brakeson the train are caused to be applied. There is also a release positionwherein the brakes on the train are caused to be released. The level ofbraking can be gradually increased by advancing the brake handle 31through the service zone. Conventionally however, especially in thefreight mode of operation, any reverse movement of the brake handle 31back through the service zone will not result in an increase inequalizing reservoir pressure. This is because automatic brake valvessuch as the Type 26™ are configured such that, with the cut off valveportion 22 positioned in the “out” or “freight” position, movement ofthe brake handle 31 back toward release position will not cause anincrease in equalizing reservoir pressure or brake pipe pressure. Inthese modes, air pressure in port P7, which is internal to the Type 26™valve, into the bottom of the equalizing reservoir cut off valve 46 isvented. This prevents pressure in the equalizing reservoir 52 fromincreasing until the brake handle 31 is placed in release position. Airthrough port P3 to port P7 under the equalizing reservoir cut off valve46 lifts the valve off of its seat and allows air to flow. In“passenger” mode, main reservoir air is present on the underside of theequalizing reservoir cut off valve 46, which allows the graduatedincreases in both the equalizing reservoir 52 and the brake pipe 3. Inthe “freight” mode, moving the brake handle 31 to release position wouldresult in a full release of the brakes, with each railcar 6 venting thebrake cylinders to atmosphere and reducing the brake cylinder pressureto zero.

Advancement of the brake handle 31 from the release position through theservice zone causes the feed valve portion 25 to reduce the pressure inpipe connection associated with ports P15 and P5, and thus theequalizing reservoir 52. This reduction in pressure is generallyproportional to the amount of brake handle 31 movement, until a totalservice reduction is obtained at full service position in the servicezone. In response to this pressure change in the equalizing reservoir52, the relay valve 28 adjusts the brake pipe 3 pressure equally asdescribed above. This reduction in brake pipe 3 pressure signals a brakeapplication in the railcars 6, and the level of braking commanded variesaccording to the position of the brake handle 31 in the service zone.

Referring now to FIGS. 3A through 4B, certain embodiments of the presentinvention will be described in detail hereinafter. FIGS. 3A and 4Aillustrate two embodiment of the invention in an inactive state, i.e.wherein the brake valve 10 controls train braking in the conventionalmanner. FIGS. 3B and 4B, on the other hand, illustrate the same twoembodiments of the invention except in the active state, wherein trainbrakes are controlled according to the invention. The basic differencebetween the two embodiments of the invention, i.e., the differencebetween FIGS. 3A–B and 4A–B, is the positioning of a pressure sensorassociated with the equalizing reservoir. In other respects, theembodiments operate in a similar manner.

Generally, and as can now be appreciated in view of the prior artoperation of the automatic brake valve 10 described above, embodimentsof the present invention provide for the use of a conventionallocomotive automatic brake valve to control braking on railcars 6 whichare equipped with ECP brake systems 7. As a result, the addition ofseparate ECP brake control equipment to the locomotive cab, such as theHEU described previously, can be unnecessary. Train operators cancontrol the speed of the train using the conventional automatic brakevalve 10 to which they have become accustomed over many years of use.Moreover, the familiar brake handle 31 can also be used as the operatorbrake control interface with the automatic brake valve 10.

As explained previously, the reference pressure, or feed valve setting,for the brake pipe 3 is established by the feed valve portion 25 whichregulates the equalizing reservoir 52 pressure to the pressure settingof the feed valve portion 25. As explained above, on one side of thefeed valve portion 25 is an adjustable screw 49, while the other siderests on a machined cam 55 on the shaft 58 of the brake handle 31. Asthe brake handle 31 is moved, various profiles on the cam 55 are movedpast the feed valve portion 25, thereby causing pressure to eitherdecrease or increase in the equalizing reservoir 52. However, asexplained above, the pressure change in the equalizing reservoir canalso be effected by the train operator using some other type of operatorcontrol portion of the automatic brake valve 10. This changed equalizingreservoir pressure is then used as pilot pressure in the relay valve 28,i.e., applied to one face of the diaphragm 66, which amplifies thesignal to cause large amounts of air to be admitted into the brake pipe3 from the main reservoir until the pressure in the brake pipe 3generally equals the pressure in the equalizing reservoir 52.

As described above with regard to the Type 26™ automatic brake valve,graduated brake release is not used in normal freight operation. This isgenerally because the brake control valves on the railcars, such asABDW™ valves, are not conditioned to provide incremental reductions inpressure from the brake cylinder. However, the automatic brake valve 10can be conditioned so that incremental reductions in brake pipe 3pressure can be made, i.e., incremental increases in braking level canbe made by moving the brake handle 31 and applied by the conventionalfreight car brake valves. The opposite, however, is not true—gradualincreases in the brake pipe 3 pressure, so as to gradually reducepressure in the railcar 6 brake cylinders, generally cannot be done.Conventionally, a brake release can only take place when the brakehandle 31 is moved to the release position. This is defined as a directrelease mode of operation. In order to provide graduated release forpassenger trains, the automatic brake valve can be conditioned, byplacing the switch 23 on the cut off valve portion 22 described above inthe passenger mode, so that incremental increases in brake pipe 3pressure can be made. In the passenger mode, movement of the brakehandle 31 toward the release position from a position in the serviceapplication zone causes the pressure to rise in the equalizing reservoir52. In response, the relay valve portion 28 causes the brake pipe 3pressure to follow the rise in equalizing reservoir pressure in themanner described above. However, operation of freight trains with theautomatic brake valve 10 configured for graduated release is notrecommended, since even a slight move of the brake handle 31 toward therelease position can cause the direct release control valves on therailcars 6 to assume a release position.

According to the present invention, use of the graduated releasecapabilities of the automatic brake valve 10 can be utilized, whilecausing the brake pipe 3 pressure to remain at some fixed value. Asshown in FIGS. 3A through 4B, various pipe and connections from theautomatic brake valve 10 are interrupted, or tapped, to providepressures which can be read by a pressure sensor 75, such as a pressuretransducer, and/or pressure switches, which are designated in thedrawing figures by the prefix “PS.” A regulating valve 81 can beutilized according to the invention to provide a reference pressure forthe relay valve portion 28 of the automatic brake valve 10. The supplypressure for the regulating valve 81 can be from a main reservoir on alocomotive of the train and, like the feed valve portion 25 of theautomatic brake valve 10, the setting of the regulating valve 81 can beadjusted via adjustment member 84, which can be accomplished viaconventional means, such as by controlling a magnet valve, or using ascrew as with the feed valve portion 25.

Additionally, an interface unit 78, which can be a simple magnet valve,can be provided to control the passage of air between the equalizingreservoir, via pipes associated with port P15, and the relay valve 28,via pipes associated with port P5. The regulating valve 81, althoughshown as a separate device, can be part of the interface unit 78.

With the power to the new interface unit 78 turned off, as shown inFIGS. 3A and 4A, the brake system functions conventionally according tothe manner described in connection with FIG. 1. Equalizing reservoirpressure, via the feed valve portion 25, is communicated through portP15 to the P2A valve 72, and then back to port P5, into the relay valveportion 28 of the automatic brake valve 10. In this manner, a reductionin equalizing reservoir pressure, caused by movement of the brake handle31, or other operator control portion, is communicated to the controlside, i.e., the outer face 63 of the diaphragm 66, of the relay valve28, which causes brake pipe pressure to mirror the new equalizingreservoir pressure setting in accordance with the operation of the relayvalve 28 described previously.

The P2A valve 72 is commonly used to signal for a full service brakeapplication upon the actuation by certain control features which may beprovided in the train braking system, such as overspeed control, traincontrol or safety control. For example, in the event of a penaltycondition, the P2A valve 72 would be actuated to block pressure fromport P15 from communicating with port P5 of the automatic brake valve10, and to exhaust pressure from port P5 to atmosphere at a servicerate. Air passages in the P2A valve 72 can also connect port P25 to mainreservoir pressure, thence, in a penalty application, air flows from theP2A valve 72 through port P25 to a pressure switch PS25, which in turncauses power to be removed from the locomotive's traction motors via a“Power Knock-Out” device, which is normally vented to atmosphere.

When energized, as shown in FIGS. 3B and 4B, the interface unit 78 isconditioned to interrupt the flow of air from port P5 of the P2A valve72 to port P5 of the automatic brake valve 10. Instead, port P5 of theP2A valve 72 is connected to the pressure sensor 75, which can generatean output signal 89 representative of the pressure being sensed.Likewise, port P5 of the automatic brake valve 10 is redirected by theinterface unit 78 to the regulating valve 81. A pressure gauge 87 can beprovided to indicate, and display, the pressure at the regulating valve81, which can be adjusted to the desired value via the adjustment switch84. As can be seen due to the different positioning of the pressuresensor 75 in FIGS. 3B and 4B, the pressure sensor 75 can be connected tothe equalizing reservoir 52 through interface unit 78 such that pressurein the equalizing reservoir 52 is sensed only when the interface unit 78is activated, i.e. FIG. 3B, or can be connected directly to theequalizing reservoir 52 such that pressure therein can be sensed whetheror not the interface unit 78 is activated.

The regulating valve 81 can be set at the typical feed valve 25 settingof 90 psig. This pressure will communicate through the interface unit 78to port P5 of the automatic brake valve 10. The connection of port P5 tothe reference pressure established by regulating valve 81 can ensurethat a constant, regulated pressure will be generally maintained on thecontrol side of the relay valve portion 28.

With the interface unit 78 in the energized state, the automatic brakevalve 10 is conditioned for graduated release mode. In this mode, thepressure delivered from port P15 of the automatic brake valve 10 willchange up or down in response to the movement of the brake handle 31through its operating range. The pressure changes resulting frommovement of the brake handle 31, or other operator control portion, aredirected to the pressure sensor 75, which can produce an output signal89. representative of the pressure being sensed. The output signal 89from the pressure sensor 75 can be communicated to the ECP controller 8by a train wireline 4, radio communication 5, or the like. However, useof RF communications would require an RLF transceiver on the locomotive1 to send the signal to the ECP equipped railcars 6 and an RFtransceiver in the ECP equipment 7 to receive the signal. The ECPcontroller 8 would likely be located on the locomotive 1, as shown inFIG. 1, and can include a processor. The ECP controller 8 can utilizethe output signal 89 from pressure sensor 75, which can be indicative ofthe expected level of braking effort commanded by movement of the brakehandle 31, or any other brake control valve interface, to determine thelevel of braking to be applied on the ECP equipped railcars 6. The ECPcontroller 8 can then generate signals used to control the ECP equipment7 via the wireline 4, or RF communications 5. For example, a range couldbe created, wherein placing the brake handle 31 in minimum serviceposition would represent a 10% brake effort. Moving then to full serviceposition would cause 100% of the braking effort, and the level ofbraking effort corresponding to positions in between would be determinedproportionally, between 10% and 100%, according to the number of degrees(the brake handle moves generally in an arc) the brake handle 31 ismoved. Alternatively, similar methods could be devised using other typesof operator control portions, besides the brake handle 31, to create asimilar range of valves which could be used to proportion the amount ofbraking desired, and which could be thus converted to a signal for usein controlling the braking on the railcars in an ECP manner.

As can be seen in FIGS. 3A–4B, the brake pipe 3 is not connected toregulating valve 81, or to the feed valve portion 25 of the automaticbrake valve 10. Consequently, when the interface unit 78 is energized,the brake pipe 3 is used only as a supply line. In this condition, thebrake pipe 3 is charged and vented by relay valve 28, which derives itscontrol signal pressure from the regulating valve 81. Thus, the brakepipe 3 is generally isolated from pressure changes which would otherwiseaffect the operation of the train brakes. Likewise, the brake handle 31can be moved incrementally back toward release position, and acorresponding reduction in braking effort will take place without anyeffect on brake pipe pressure.

One scenario for changing over train braking system from conventionalpneumatic operation to ECP operation could be to configure the systemsuch that the brake handle 31, or other operator control portion, mustbe in release position prior to enabling the interface unit 78. Next,the brake handle 31, or other operator control portion, would be movedto the suppression position, where a reading of the maximum pressurereduction is made. Finally, the brake handle 31, or other brake controlvalve interface, can be moved to the release position and the interfaceunit 78 can be energized. The state change in the interface unit 78would turn response of the automatic brake valve 10 over to the ECPbraking system.

In addition to the basic operation of the system described above,various other pressures can be read by pressure switches, indicated bythe prefix “PS,” to permit the interface unit 78 and ECP system 7 toderive certain information from the pneumatic brake equipment which canbe used to perform specific functions. For example, port P3 of theautomatic brake valve 10 is typically pressurized only when the brakehandle 31, or other operator control portion, is in the releaseposition. By monitoring the status of port P3 through the interface unit78, the ECP system 7 could establish the normal, zero percent brakingbaseline. In similar fashion, port P26 is typically pressurized onlywhen the brake handle 31 is in suppression positions, or beyond. Thissignal could be used to determine the maximum braking effort, since thereduction in brake pipe pressure is the same in suppression as is in thefull service position. The scenario for changing to ECP mode could beset up so that the brake handle 31, or other operator control portion,must be in release position to energize the ECP interface unit 78. Thebrake handle 31, or other operator control portion, could then be movedto the suppression position, where a reading of the greatest reductionis made. At that point, the brake handle 31, or other operator controlportion, can be moved to the release position to energize the interfaceunit 78. The state change in the interface unit 78 would turn responseof the automatic brake valve 10 over to the ECP system 7.

Other pressures monitored could include port P25 of the P2A valve 72 andports P9 and P35 of an A1 charging cut-off valve, another valve commonlyused in this type of braking system. Inputs to the various pressureswitches would take place during events such as penalties oremergencies. Under software control, the ECP system 7 could then makedecisions regarding the control of the train brakes.

The invention thus allows a train operator to control braking on ECPequipped railcars 6 using the familiar pneumatic brake handle 31, orother operator control portion, on a conventional automatic brake valve10 with which the train is conventionally controlled. Consequently, theamount of training required on new equipment can be lessened, and theplacement of additional hardware in the cab of the locomotive can beavoided.

Although certain embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications to those details could be developed in light of theoverall teaching of the disclosure. In particular, it is to beunderstood that the invention is not limited to application with onlythe Type 26™ automatic brake valve or using a “brake handle, but can beutilized in accordance with the teachings herein with any similarlyfunctioning automatic brake valve, or operator control portion whichcontrols the train brakes via conventional automatic brake valve andusual pneumatic connections with, for example, a brake pipe, equalizingreservoir, relay valve, feed valve, main reservoir, and the like.Moreover, since the railroads, and also federal regulations concerningtrain operation, cover most aspects of train brake control systems,most, if not all, automatic brake control valves typically operate ingenerally the same manner and provide generally the same functions.

Accordingly, the particular embodiments disclosed herein are intended tobe illustrative only and not limiting to the scope of the inventionwhich should be awarded the full breadth of the following claims and anyand all embodiments thereof.

1. A method for controlling electro-pneumatic brakes on a train ofrailcars from a conventional pneumatic brake control valve on alocomotive interconnected with said train of railcars by a brake pipeand a brake control signaling system, said method comprising: a.initiating a pressure change from said conventional pneumatic brakecontrol valve, said pressure change representative of a pneumatic brakecommand; b. sensing said pressure change; c. producing an electricalsignal corresponding to said pressure change; d. communicating saidelectrical signal to braking equipment on said railcars via said brakecontrol signaling system; e. controlling braking on said railcars basedupon said electrical signal; and f. preventing a change in brake pipepressure responsive to said pressure change.
 2. The method of claim 1further comprising generally maintaining said brake pipe pressure at apredetermined level.
 3. The method of claim 1 wherein initiating saidpressure change comprises manipulating an operator control facility of abrake valve on said locomotive.
 4. The method of claim 3 whereinmanipulating said operator control facility further comprises moving abrake handle.
 5. An apparatus for controlling electro-pneumatic brakingon a train of ECP equipped railcars using a pneumatic brake valvelocated in a cab of a locomotive of the train, said locomotive and ECPequipped railcars interconnected by a brake pipe and a brake controlsignaling system, said apparatus comprising: a. an operator controlportion connected to said brake valve and operable to cause a pressurechange representative of a pneumatic brake command; b. a relay valve incommunication with at least said brake valve and said brake pipe, saidrelay valve conventionally causing pressure in said brake pipe to mirrorsaid pressure change; c. an interface unit in communication with atleast said relay valve, said interface unit controllable to isolate saidrelay valve from said pressure change such that said relay valve doesnot mirror said pressure change in said brake pipe; d. a pressure sensorcommunicating with said brake valve at least when said interface unitisolates said relay valve, said pressure sensor producing a signalcorresponding to said pressure change; e. an ECP controller receivingsaid signal and controlling braking on said railcars based upon saidpressure change via said brake control signaling system; f. anequalizing reservoir in communication with said brake valve, said relayvalve, and said pressure sensor, said pressure change caused in saidequalizing reservoir by said brake valve; g. said interface unitinterposed between said equalizing reservoir and said relay valve forisolating said relay valve from said pressure change caused in saidequalizing reservoir; and h. said interface unit interposed between saidequalizing reservoir and said pressure sensor, said interface unitconnecting said equalizing reservoir with said pressure sensor whileisolating said relay valve portion from said equalizing reservoir andconnecting said relay valve to a reference pressure source.